A typical example of an exposure apparatus used to manufacture a device, such as a semiconductor device, includes a step & repeat exposure apparatus (stepper), which sequentially exposes the pattern of a master (reticle or mask) onto a plurality of exposure regions on a substrate (e.g., a wafer or glass substrate) through a projection optical system while stepping the substrate, and a step & scan type exposure apparatus (scanner), which repeats stepping and scanning exposure to repeat exposures and transfer on the plurality of regions on a substrate. In particular, the step & scan type exposure apparatus uses exposure light after limiting it with a slit to a component comparatively close to the optical axis of a projection optical system, so that it can expose a micropattern at a higher accuracy with a wider angle of view. Some exposure apparatuses draw a pattern on a substrate with an electrosensitive particle beam, such as an electron beam or ion beam, in place of light.
Each of the exposure apparatuses has a stage device or driving apparatus (wafer stage or reticle stage) which aligns a wafer or reticle by moving it at high speed. In such an exposure apparatus, when the stage is driven, a reaction force of an inertia force accompanying acceleration and deceleration is generated. When the reaction force is transmitted to a stage surface plate on which the stage is mounted, the stage surface may swing or vibrate. Such vibration induces characteristic vibration of the mechanism system of the exposure apparatus to generate high-frequency vibration which may interfere with faster, higher-accuracy alignment.
To solve the problems relating to the reaction force, several proposals have been made. For example, according to the apparatus described in Japanese Patent Laid-Open No. 5-77126, the stator of a linear motor which drives a stage is supported on the floor independently of a stage surface plate, so that swing of the stage surface plate caused by the reaction force is prevented. According to the apparatus described in Japanese Patent Laid-Open No. 5-12.1294, a machine frame supports a wafer stage and projection lens. An actuator which generates a force in the horizontal direction applies to the machine frame a compensating force equivalent to a reaction force accompanying the drive of the stage. Swing of the apparatus caused by the reaction force is thus decreased.
In any of the conventional examples described above, although the swing of the stage apparatus itself can be decreased, the reaction force accompanying the drive of the stage is transmitted to the floor directly or through a member that can be substantially regarded as being integral with the floor. This may oscillate the floor and vibrate devices set around the exposure apparatus, thus, adversely affecting the peripheral devices. Usually, the floor where the exposure apparatus is installed has a natural frequency of about 20 Hz to 40 Hz. As the exposure apparatus is operated, when the characteristic vibration of the floor is induced, it adversely largely affects the peripheral devices.
Recently, as the processing speed (throughput) increases, the stage acceleration increases more and more. For example, in a step & scan type exposure apparatus, the maximal acceleration of the stage reaches as high as 4 G in the reticle stage and 1 G in the wafer stage. As the reticle or substrate increases in size, the stage mass also increases. Therefore, the driving force defined by <mass of a moving object>×<acceleration> becomes very large, and its reaction force is enormous. As the reaction force increases in this manner, oscillation of the floor for installation caused by the reaction force has become a non-negligible issue.
The size of the apparatus also increases largely, and in a manufacturing factory where many manufacturing apparatuses are installed, an increase in an area occupied by the apparatuses is becoming an apparent issue. More specifically, when the vibration transmitted from one apparatus to the floor is large, to prevent the other apparatuses from being influenced by the vibration, the distances among the apparatuses must be increased, and finally, the area actually occupied by the respective apparatuses increases.
Japanese Patent Laid-Open No. 2003-318082 discloses, in a driving apparatus which drives an object by a linear motor, use of the stator of the linear motor as a reaction force counter. According to the driving apparatus described in this document, when an object which stays still at the first position is to be moved to the second position and be set still, the linear motor is controlled so that the object moves along a straight line connecting the first and second positions, to cancel a moment reaction force accompanying acceleration and deceleration of the object.
According to the technique described in Japanese Patent Laid-Open No. 2003-318082, the wafer stage must be moved along a straight line. In the step & scan type exposure apparatus, assume that the entire moving path of a wafer stage to sequentially expose a plurality of exposure regions S is formed of straight lines, as shown in FIG. 5. The wafer stage must be stopped at the terminal point of each straight line. This can interfere with an increase in throughput. In view of this, to sequentially expose the plurality of exposure regions S while continuously driving the wafer stage along a smooth curved line, as exemplified in FIG. 6, is sought.
To continuously move the wafer stage along the smooth curved lines, moderation of the limit for a Y-direction (X-direction) driving pattern by an X-direction (Y-direction) driving pattern (driving profile) is sought.